1. Field of the Invention
The present invention relates to a coupling, and more particularly to a coupling for securing a handlebar stem of a bicycle.
2. Description of the Prior Art
A typical fixing device for securing handlebar stem is disclosed in U.S. Pat. No. 4,274,301 to Katayama, filed Jun. 30, 1978, entitled "HANDLE STEM FIXING DEVICE FOR A BICYCLE AND THE LIKE". In this patent, a cone 3 is threadedly engaged on the lower end of a bolt 2 and caused to move radially outwards in order to fix the handle stem 5. However, an opening should be provided in the upper end of the handle stem 5 and the head 21 of the bolt 2 should be exposed such that the bolt 2 can be rotated; which means, water and dust may enter into the handle stem 5 easily, such that the parts are apt to be rusted.
Another type of coupling for securing a handlebar stem which is commercially available is shown in FIG. 5 and comprises a tube 41 engaged on the upper end of the front fork 30, and a shank 40 having one end fixed on the tube and having the other end for supporting the handlebar (not shown); the tube 41 includes a split 43 vertically formed therein in order to form a pair of adjacent edge portions and includes four lugs 42 formed integral on the edge portions respective such that the edge portions can be fixed together by two bolts 44. The lugs 42 and the bolts 44 are exposed and are apt to be rusted, in addition, the exposed configuration spoils the outer appearance of the handlebar stem.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional couplings for securing handlebar stems.